194 BERRY— LOWER EOCENE FLORA OF [April 25, 



family contains twenty monotypic genera distributed as follows : 

 Asia 5, Australia 3, Africa 6, Madagascar 3, North America 2, and 

 South America i. 



The fossil records of the Anacardiacese are very incomplete 

 although there seems to be no doubt that it was represented in both 

 Europe and North America as far back as the Upper Cretaceous. 

 As in the existing flora the most abundant genus in the fossil record 

 is Rhus to which over one hundred species have been referred. Eight 

 of these are Upper Cretaceous forms the oldest coming from North 

 American strata correlated with the Cenomanian (Raritan, Dakota). 

 The genus appears in Europe in the Turonian of Bohemia. There 

 are over a dozen Eocene species of Rhus, widely scattered. Thus 

 there are three in the Ypresian of Alum Bay, four in West Green- 

 land and North American species in the Lance, Kenai, Ft. Union and 

 Green River formations. The genus doubles its known species in the 

 early Oligocene, being especially well represented in southern France, 

 but also recorded from the Tyrol, the Baltic amber, Italy, Carniola 

 and Styria. 



In the Miocene Rhus seems to have been as abundant, as well 

 differentiated, and as widely distributed as it is in the existing flora, 

 for over sixty fossil species have already been described. The 

 records embrace all European countries where Miocene plants have 

 been found as well as Iceland and the following North American 

 localities : — Maryland, Virginia, Colorado, Yellowstone Park, Idaho, 

 Nevada, Oregon and California. Only a small number of Pliocene 

 species are known and these are recorded in Spain, France, Italy, 

 Germany and Slavonia. 



Three Pleistocene species are recorded, 2 from Japan and one 

 from China, all closely related to still existing species of that region. 

 Engler^'' some years ago reviewed the geological records of Rhus 

 and concluded that most of the then known fossil species belonged to 

 the section Trichocarpge (in the existing flora with over a score of 

 species mostly confined to North America and eastern Asia), or the 

 section Gerontogeas (with 75 existing species mostly confined to 

 South Africa). A few fossil forms he considered as representing 

 the section Venenatre, which has about 14 existing species in North 



35 Engler, A., Bot. Jahrb., Bd. i, i88r, pp. 413-419. 



